Instantaneous data of fuel-air mixing is important to design the supersonic combustor, but they are difficult to measure in the supersonic flow-field. Planar Laser Induced Fluorescence (PLIF) using two PLIF tracers is one of promising methods to measure them in the supersonic flow. We use acetone and toluene as PLIF tracers because they can be excited with single excitation laser and their fluorescence spectrum are separated. The problem of this method are temperature and surrounding-gas dependence of their LIF signal intensities and saturation of toluene LIF by excitation laser. In this work, the effects of surrounding gas and temperature against toluene LIF intensity and toluene LIF saturation are investigated.

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Unsteady PSP technique to detect small unsteady pressure fluctuation is required to minimize its noise level and improve detection limit. One approach to update a high-speed camera, which had larger sensitivity, was investigated its performance to decrease the unsteady PSP measurement system noise. Two types of system tests, which were an AA-PSP sample test and a wind tunnel test using NACA0012 model, was conducted. Larger sensitivity camera could reduce noise floor and its factor was from 3 to 6. Detection limit using a larger sensitivity camera was 20Pa2 for the 10,240 images AA-PSP sample test and 3Pa2 for the 46,592 images wind tunnel test.

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In this paper, we measure the surface pressure distribution of a rotating fan using a silica nanoparticle pressure-sensitive paint (PSP), which is a sprayable fast-responding PSP. In order to compensate the temperature sensitivity of the PSP, we simultaneously measure the temperature distribution using a polymer-based temperature sensitive paint (TSP). The experimental results show that, in order to obtain small variety of pressure distribution, the raw images of actual (rotating) condition must be adjusted to the image of reference (still) condition within one pixel. Non-uniform distribution of residual moisture content in PSP layer disturbs the accurate pressure measurement.

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This paper describes visualization and measurements of pressure distribution by using Pressure-Sensitive Paint (PSP) for externally pressurized thrust gas bearing. The test bearing diameter is 30 mm. Numerical calculation of pressure distribution was carried out using divergence formulation method. Obtained results by experiments were compared with calculated results, it was quantitatively evaluated.

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Porous pressure sensitive paint (PSP) having fast response and high pressure sensitivity will be a powerful measurement tool to diagnose flow properties in consumer turbomachinery. We have composed test facilities of a turbofan with a transparent casing, to apply a fast-response PSP to measurement of nonstationary pressure distribution on the casing surface of the turbofan. However, luminescent intensity of the PSP without a white undercoat acting as a screen layer is relatively low, which results in low signal-to-noise ratio for pressure measurement. In this study, we have examined the effect of white overcoat with high oxygen permeability made of boron nitrate (BN) nanoparticles, which functions as a screen layer to enhance the luminescence intensity of the PSP through a transparent surface. We have clarified that the BN overcoat can enhance the luminescence intensity and SN ratio of PSP without affecting the time response.

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The objective of this study is to obtain the pressure distribution on a rotating disk surface using PSP(Pressure-Sensitive Paint). Platinum(II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) is used as a luminophore of PSP. The change in pressure on the rotating disk (radius is 150mm) is small, and under 3kPa from the reference pressure. However, it is shown that the surface pressure increases as quadratic function from the center to the disk edge and the change of pressure in the radial direction becomes larger with increasing the rotating speed (2000-4000rpm).

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Temperature and oxygen sensitive hollow micro capsules were fabricated using the bubble template method. The micro bubbles were nucleated in droplets of a dichloromethan solution of polymer. The polymer covered micro bubbles were suspended in aqueous solution. The dichloromethan solution of temperature and oxygen sensitive dye was dissolved into the polymer solution and the temperature and oxygen sensitive dye was incorporated into the capsule shell. Using the bubble template method, large amount of hollow micro capsules could be formed with very high number of density. The diameter of capsules was smaller than 1 micro meter. It seemed to be suitable as tracer particles for the PIV measurement. The temperature sensitivity and the oxygen sensitivity of fluorescence intensity from the functional capsules were measured using a spectrometer. The effect of excitation wavelength on these sensitivities and the quenching due to large excitation intensity were also evaluated. The temperature sensitivity was about -2%/°C and the fluorescence intensity was stable and no quenching was detected in 20 minutes, even under the intense excitation of 1W.

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The pressure-sensitive paint (PSP) technique is an optical technique for measuring surface pressure on a model surface. The PSP technique has been used in wind-tunnel tests because of its great advantages such as non-intrusive and global pressure measurement. In general, PSP is painted by a sprayer by hand, resulting in low reproducibility. In this study, we used a commercial inkjet printer for printing PSP on substrates. PSP was printed on three substrates: chromatography paper, label seal, and viewgraph. We investigated the pressure and temperature sensitivities of these PSPs. PSP printed on the chromatography paper showed the best characteristics among them. And, we succeeded in preparation of PSP using the commercial inkjet printer.

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A sprayable fast pressure-sensitive paint (PSP) has been developed to measure pressure fluctuation on models made of non-aluminum-alloy materials with complex shapes. It is important to distribute a pressure-sensitive dye only over the surface to improve responsiveness of the fast PSP. In this study, fast PSP's were prepared by applying the solution of a pressure-sensitive dye onto a pre-coated porous binary layer and the effect of the solvents of dye solution was investigated. By choosing a polymer dissolving solvent for the dye solution, one could succeed to develop a PtTFPP based PSP with a pressure response time of 17.8 μs at 90 % pressure rise to a step change of pressure. This was about 10 times faster than a previous fast PSP (191μs) using a polymer dissolving solvent for dye solution.

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We have been developing a temperature-sensitive luminescent coating (LC) for surface temperature measurements in microchannels. In the present work, a free-base porphrin complex with pentauorophenyl esters in the side chains was synthesized and then covalently attached to indium tin oxide (ITO) glass to make the temperature-sensitive LC. The absorption spectrum of the developed LC retained the characteristic shpae of that of the free-base porphyrin disolved in dichloromethane. While the temperature sensitivity of the present LC was comparable to that of the previously developed LC of Pt(II)-porphyrin, the pressure sensitivity of the present LC was much smaller than that of the LC of Pt(II)-porphyrin.

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In the present study, the method for the correction of delay in the AA-PSP data is proposed. This method is applied to the AA-PSP data measured in a cavity flow that oscillates at several kilohertz. As a result, the corrected PSP data agree well with the data measured with the semiconductor-type pressure transducer; that is to say, the proposed method can be applied to correct the delay appearing in the AA-PSP data measured in oscillatory flows whose frequencies are too high to capture with the AA-PSP.

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The PSP measurement technique is a non-contact pressure measurement method based on the oxygen quenching of the luminescence. Since the luminescence intensity of PSP depends on temperature as well, PSP result has to be corrected by the temperature distribution on the measurement surface. Also, position misalignment between wind-on and wind-off images reduces the measurement accuracy in the PSP measurement. In order to correct the temperature effect, combined PSP and TSP sensors such as mixture sensor, multi-layers sensor and multi-arrays sensor have been developed. Among these sensors, the multi-arrays sensor is favorable sensor from a view of the interaction between PSP and TSP luminophores. In this study, we attempt to correct the positon misalignment between wind-on and wind-off images by using the dot arrays of the dual-array sensor as markers. The result shows that it is possible to roughly correct positions between wind-on and wind-off images, but the correction accuracy is not enough yet.

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The present study focuses on the turbulent natural convection heat transfer in a cubical enclosed rectangular container. The container is composed of the heated and the cooled side plates. The working fluid is water to attain larger value of Rayleigh number. The numerical simulation with LES is conducted at the same time in order to elucidate the experimental result with PIV and LIF methods. It is obvious that the heat transfer coefficient using simulation with LES is well correlated with that of the experimental investigation.

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We present an experimental study on the dynamics of a starting plume induced by rectangular heating surface. Starting plume is the initial stage that thermal plume induced by a heating surface. It is difficult to measure the scaling of starting plume, because the flow pattern of scaling is complex. In the present study, PIV measurement is applied to the starting plume. Results show that there are two plumes induced at the edge of heating surface in the initial stages. Then two plumes join with each other, and finally form one unified object. In addition, the characteristics of starting plume are also studied by numerical simulation. It is found that the velocity field of starting plumes obtained by the experiments in accordance with that obtained by the numerical simulation. The temperature fields obtained by the numerical simulation provide a reference base for the LIF measurement in the future research.

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In this study, we propose a temperature measurement method that uses ultra-fine fluorescent wires. This is possible because its structure is simple, and any material can be used for the wire. Hence, ultra-fine wires whose Reynolds number is less than 1.0 can be selected. This means that turbulent flow is not generated downstream of the wire and that its wake is negligibly small. Fluorescent paint (containing Rhodamine B) was coated on the surface of the wires. The test volume was illuminated by using UV lights. The paint emits a very tiny orange-colored fluorescent light whose intensity changes with the temperature of the atmosphere. A very high sensitivity color camera (Nikon D7100, ISO 25600, 14 bit, 6,000×4,000 pixels) was used to record the visualized image.

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Recently, heat transfer enhancement in an automotive heat exchanger becomes one of key technologies. Then, a flow in tube of heat exchanger has a low Re number. For heat transfer enhancement, the saliences are designed on the inner surface of tube. Saliences promote turbulent flow and mixing effect, at low Re number, even though a turbulent flow is vanished by viscous effect. The saliences which promotes continuous turbulence is needed. For this reason, we have carried out a flow visualization experiment. Temperature contour has been visualized with liquid crystal thermometry. And, 3D particle tracking velocimetry has also conducted for visualization of turbulent generation. So, heat transfer performance has been evaluated with the experimental results.

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In this study, we developed a microfluidic temperature imaging method and system using the fluorescence anisotropy of fluorescent dye. The fluorescence anisotropy is independent on the distribution of observation depth or dye concentration and the quenching, so that the imaging technique is suitable to measure temperature in versatile microfluidic systems. To verify the superiority of the measuring method to the conventional approach based on thermal quenching, laser-induced fluorescence, the dependence of channel depth and the influence of the fluorescence quenching by strong light irradiation were evaluated. Moreover, the temperature distribution of liquid under local heating by laser was successfully measured.

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This study reports simultaneous measurement of flow field and liquid layer thickness to evaluate sensible and latent heat transfer during pool boiling. Particle image velocimetry(PIV) captured flow field near a heat transfer surface and back light method clarified liquid layer structure beneath bubbles. A narrow pool sandwiched by two transparent plates was employed as a test section to constrain boiling bubbles for observation and illumination. PIV results illustrated bubble departure induced the flow toward the heat transfer surface and magnitude of the flow increased with the increasing heat flux. Liquid layer at relatively high heat flux covered the heat transfer surface widely and it was thinner than that at low heat flux. This indicates latent heat transfer with liquid layer evaporation played a dominant role at high heat flux. Simultaneous measurements revealed that temporal tendencies of sensible and latent heat transfer were strongly linked, and reached their peaks at bubble departure.

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This study measured temperature distribution and its time variation of a thin plate with a micro-gap channel to investigate cooling condition of flow boiling to guarantee the operation temperature of electronic devices. The thin plate was heated with a thin film heater and the heater was coated with temperature sensitive paint(TSP) made of ruthenium complexes. Highspeed camera recorded the distribution of fluorescence intensity of TSP with the resolution of 0.07mm in space and each intensity was converted into temperature pixel by pixel with the resolution of 0.25℃ in temperature. Flow boiling experiment revealed that stagnant boiling bubbles led to local and temporal temperature rise.

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Compression type refrigerator has been used as automotive air conditioner, so we need additional fuel for air conditioning. Absorption chiller is heat driven type refrigerator, so when we adapt it for automotive air conditioner and use with waste heat, it will reduce the fuel consumption. We are developing the absorption chiller for automobile which have the tolerance for unique environment of automobile. In this work, we propose new type absorber which has heat exchanger smeared lithium-bromide(LiBr) solution by rotors with brushes. And now, wet area of heat exchanger is important factor for the performance. In this paper, the method to visualize the liquid film flow of solution is established by using laser and fluorescent agent, and wet area of surface of heat exchanger is quantified.

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This paper describes measurement results of leading-edge separation-bubble length on a flat plate at low Reynolds numbers applying a luminescent oil film technique (GLOF), which allows us to calculate a quantitative reattachment point based on the skin friction vector. The present results are compared with previous experimental data obtained by a water channel and a low-density wind tunnel. A common trend that the separation-bubble length increases and gradually decreases with Reynolds number increasing is observed. However, the results have differences in the peak Reynolds number and separation bubble length even between wind tunnel data.

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In this study, the result of correlative relation between the heat transfer and flow behaviours near wall region in the turbulent boundary layer is presented. The instantaneous flow and temperature distributions are simultaneously measured by using stereo PIV system (velocity distributions of 2 dimensions and 3 components) and the high-speed infrared thermography. Using this system, the unsteady flow behaviours at the xz cross section and heat transfer on the heated wall are investigated in the Reynolds number range from 610 to 2,200. In order to discuss the correspondence of the near wall flow and the heat transfer, cross correlation coefficient of instantaneous these distributions is calculated, and it seems that the fluctuations of the forward and downwash flows near wall region corresponds to that of the heat transfer enhancement on the heated wall.

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Simultaneous CH-OH planar laser induced fluorescence (PLIF) and stereoscopic particle image velocimetry (SPIV) measurements at 10 kHz have been conducted in a methane-air turbulent jet premixed flame. Around the flame tip in the high Reynolds number condition, the fine scale unburned mixture islands are ejected downstream. The enhancement of the turbulent burning velocity is statistically analyzed by the local consumption rate, which is estimated from the OH and CH PLIF images with the assumption of the spherical and pillar shapes of the unburned mixture. The most probable consumption rates with different methods give significantly higher burning velocity than the laminar.

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It is important to improve the power generation efficiency of polymer electrolyte fuel cell (PEFC). In this study, we visualized a partial pressure of oxygen at a surface of gas diffusion layer (GDL) in a cathode of an operating PEFC using the oxygen sensitive luminescent polymer. It was confirmed that the PEFC performance wasn't affected by painting the polymer on the GDL. We would inspect a characteristic of the oxygen consumption by the shape of gas flow channel by visualizing the oxygen distribution in the gas flow channel.

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A lifetime-based combined measurement of temperature and velocity had been proposed in the previous studies. Temperature sensitive luminescent were utilized as tracer particles of the particle image velocimetry. Temperature was estimated from the luminescent lifetime of particles. In the present report, an error analysis of velocity and temperature measurement in the combined method was done by using simulated images. As results, the accuracy of velocity measurement wasn't much affected by a small displacement of particles, number density of particles, excitation intensity and its non-uniformity. The temperature estimation was relatively affected by the large displacement of particles.

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The mixing method is highly desired in the micro scale flow. This study is an experiment to measure the mixing characteristics of temperature difference counter flow in a T-shaped submilli channel. The PIV and LIF measurements were executed to the mixing region of the channel. We used hollow microcapsules as the tracer of PIV measurement. Rhodamin B was selected as the temperature sensitive fluorescence dye. Regardless it is low Re number region, rapid movements are observed at the moment of power input. There are strong shear stress across the z-axis direction. We investigated the characteristics of the flow detail.

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The current status of pressure sensitive paint (PSP) and temperature-sensitive paint (TSP) has been presented in this paper. PSP and TSP are molecular imaging techniques and enable to measure global pressure and temperature distribution on a model surface. PSP has been achieving a remarkable improvement in responsiveness and detecting resolution of pressure. TSP is used to measure not only temperature distribution but also heat flux and to detect boundary-layer transition.

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The properties of ultrasonic propagation velocity in MR fluids (MRF122-EG and MRF132-DG) are studied experimentally. We measured ultrasonic propagation velocity with the pulse method. We used AC magnetic fields with the frequency of 1 Hz and 2 Hz, and the intensity of 50 mT and 75 mT. The change of cluster formation were confirmed by applying different frequency or magnetic flux density.

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Thermophysical property of magnetic fluid is varied by applying external magnetic field related with magnetic field intensity, magnetic field direction and elapsed time of applying magnetic field because of the cluster formation. In this study, dependence of time variation in thermal diffusivity of magnetic fluid on magnetic field intensity was investigated experimentally. Forced Rayleigh scattering method, which has high temporal and high spatial resolution, was applied to measure time variation of the thermal diffusivity of magnetic fluid. The results show that the strong anisotropy of thermal diffusivity is obtained by applying strong magnetic field and thermal diffusivity changes over the time of applying magnetic field. In contrast, anisotropy of thermal diffusivity is hardly observed when the weak magnetic field is applied to magnetic fluid.

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Magnetic fluid is stable colloidal dispersion including magnetic nano particles in a carrier fluid such as water and Kerosene. Magnetic fluid spikes are formed by magnetic field. In this paper, a novel discharge device using the magneitc spikes for air pollution control was developed. The magnetic spikes were applied as an innovative fluidic electrode controlled by magnetic field. The concentrated electric field at spike results in the discharge above tips of the spikes and the induced flow of magnetic fluid. The discharge and the interface behavior were investigated experimentally. The cleaning ability of the device was evaluated by measuring ozone production and ozone production efficiency.

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Cavitation bubbles generated by an underwater shock wave formed microjets during the collapse and rebound process and they were visualized by a high-speed camera. The directions of the microjets showed the same direction of the initial shock wave propagation. These results imply that the direction of the microjets were affected by the compression wave not expansion wave which was generated by reflection at an interface between water and air.

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MR (Magnetorheological) fluids are the suspensions composed of micron-sized ferromagnetic particles dispersed into carrier oil, and are one of smart fluids which can be changed their rheological properties in reversible manner by applying magnetic field. From the viewpoint of the applications, the no-field initial viscosity of the MR fluids should be regulated as low as possible to minimize the energy loss, and the operating temperature should be higher. However, since the carrier medium is a liquid, the limits of the viscosity minimization and the operating temperature exist. In this research, in order to develop of the MR fluid of extremely low no-field viscosity and higher operating temperature, novel "dry MR fluids" have been fabricated, and the fluidity and MR properties have been measured and evaluated. The dry MR fluid is a novel MR fluidic powder, which is mainly composed of micron-sized carbonyl iron particles coated with nano-sized particles without liquid medium.

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Magnetic functional fluids whose base fluid is polyalphaolefin containing needle-like particles are prepared as new working fluids for damping force variable dampers. Damping force of the damper using the magnetic functional fluid is measured and it is shown the basic damping property. Viscosity of the fluid is also obtained by using the rheometer. When the total volume fraction of particles in the fluid is constant, larger volume fraction of needle-like magnetic particles in the suspended particles increases the damping force.

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MR fluid is a functional fluid whose viscosity changes with magnetic field. It has been used for torque transmission mechanisms. But there are few data about its durability. The allowable centrifugal acceleration and expected torque are calculated. Magnetic field analysis was conducted for the development of a durability test apparatus using a permanent magnet. The structure consists of the upper part with a yoke, a doughnut-shaped neodymium magnet, spaces, a disk and MR fluid. The fluid gap has the V shape-type structure in order to arrange MR fluid only in the measurement part.

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A magnetic field applicable MR fluid shear flow device consisting of circular gap between rotational and fixed disks has been developed to visualize the formation and breaking behavior of the particle cluster or column in shear flow mode of MR fluids under relatively strong magnetic field up to about 0.8 T. The closed magnetic circuit with less magnetic loss is designed to apply a strong uniform magnetic field to the MR fluid filled in the circular gap between rotational and fixed disks using the JMAG magnetic field analysis software. The rotational disk is driven to induce the shear flow at a constant shear rate by a speed controlled motor. In this paper, the details of the design are described and the measured magnetic field applied to the MR fluid are compared to the numerical estimated results. The developed MR fluid shear flow device successfully performed the visualization of the formation and breaking behavior of the particle column in the shear flow mode.

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Innovative energy conversion device has been developed for efficient wind energy utilization. This device has co-axial configuration and the rotational speed of the turbine can be kept constant by controlling rotational torque by Lorentz force with electrical power generation. The dynamic characteristics of the electromagnetic energy conversion device has been experimentally clarified. For a step-like change in input torque, both rotational speed and electric output power transiently increase and then decrease to a steady value with linearly increasing applied magnetic flux density. In case of a step-like change of input torque, it was clarified that the rated speed operation is realized with partially converging the rotational energy into electric power.

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An innovative coaxial MHD power generator using low-melting point alloy has been proposed for efficient wind power generation. MHD power generation is a kind of the direct-electricity-generation method. In order to develop the generator, three dimensional MHD Taylor Couette flow is simulated using lattice Boltzmann method for MHD based on Dellar 's model. In this study, the coaxial MHD power generation characteristic using the low-melting-point-alloy is investigated at low Reynolds numbers. As the obtained results, the velocity profile is changed due to the effect of the Lorentz force. And output voltage increases linearly with the Reynolds number while sticking Hartmann number to 4.

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CO_2 is attractive as a working fluid due to GWP of CO_2 being much less than R134a. Supercritical CO_2 Solar Rankine System (SCSRS) has been proposed for both electric power generation and thermal energy supplies. In order to optimize the SCSRS, the solar collectors have to be considered in much more detail. In the present study, arrangements of array of solar collectors are studied, in consideration of series or parallel arrangement, for estimating the energy collecting efficiency. From the experimental results, it was found that with keeping the same mass flow rate, in a summer time operation, the series arrangement of solar collectors gave highest performance characteristic of heat collection efficiency of the system.

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Water solution of volatile organic compounds (VOCs) in air, especially explosive materials, is required to detect VOCs by biosensors efficiently. We developed a collecting device like olfactory mechanism of animals: thin film of water including odorant binding proteins (OBPs), which play a major role in transport of hydrophobic odor molecules to olfactory receptors. Thin liquid film was generated using rimming flow on the inner surface of a rotating glass cylinder. Eugenol was used to simulate an explosive substance. The sample gas including dilute eugenol was collected by the rimming flow device. The experimental results showed that the efficiency for the collection of eugenol increased with the revolution rate of the cylinder. Increase in the efficiency was mainly attributed to the spread of the liquid in the cylinder. The collection efficiency further increased by the adding of both proteins and PBP1 exhibited higher affinity for eugenol.

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In order to clarify the major factor of a narrowband noise in the off-design point of a propeller fan, the relative flow field in the blade tip is measured by a hot-wire probe with the phase-lock method. When the propeller fan is operated at the off-design point, the narrowband noise is generated in the lower frequency domain than that of the blade passing frequency. The velocity fluctuation in the leading edge of the blade tip became large at the same frequency band of the narrowband noise.

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In plants, pressure fluctuation in specific frequency occurs by operating fluid machinery such as a pump. If the frequency is consistent with that of pipe liquid resonance, the large vibration of the pipe and machinery may be induced. In this study, unsteady pressure in an air test model of diffuser pump was measured to clarify the generating mechanism of the pressure fluctuations. It is found that there are two types of resonances, "air column resonance" and "pressure fluctuation induced by rotor stator interaction". Moreover, it is clarified that the pressure fluctuation by resonance is decreased by setting an orifice at a node of a standing wave by echo sound test using a speaker. Also it is clarified that the smaller opening ratio of the orifice is, the larger the pressure fluctuation is decreased.

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A micro wind-power generation unit driven by longitudinal vortex induced vibration that is used for a power supply of stand-alone sensor is investigated. In this work, a module that has 4cm x 4cm in the inner cross section is tested. A oscillator cylinder is 6mm diameter and the splitter-plate to induced the longitudinal vortices is 6mm in width. Two sizes of the height of the splitter-plate are tested to evaluate the effect of block ratio, which is the ratio of a cylinder and a wake plate to the channel cross section. The necklace vortex induced vibration is not strongly generated in both splitter-plates. However, a new type of vibration is observed in s/d>1.00, here s the gap between the cylinder and the splitter-plate and d is the diameter of the cylinder. In this state, the shorter height splitter-plate generates lager amplitude of the oscillation. The block ratio for the shorter and longer splitter-plate are 0.18 and 0.23, respectively, and it is not serious deference to induce the deference of the amplitude. Therefore, the geometrical effect of the splitter-plate or wall effect would be dominated.

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In order to reproduce the real driving condition of an automobile in the laboratory, the door mirror noise of the automobile was estimated by the wind tunnel test giving the uniform flow. Moreover, the scale model of the door mirror was analyzed by the wind tunnel for clarifying the relationship between the flow field around the door mirror and the aerodynamic noise. In particular, we discussed the low frequency narrow band noise and the flow field around the door mirror because the noise was 10dB larger than the background noise in the real automobile wind tunnel test. The experimental results indicated that when the clearance between the base and the visor of the door mirror is changed it influenced to the noise level in the low frequency domain. The noise level was increased due to the width of the wake when the clearance between the base and the visor was increased. From above results, we could grasp the phenomena about the narrow band noise in the vicinity of the 300 Hz generated from the actual automobile door mirror as it caused by the vortex shedding from the base.

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The purpose of the study is to clarify the forces on the mirror surface generated aerodynamically by separating vortices. CFD reveals that separating vortices with the frequency of 25 Hz have dominant effects on the mirror surface and the generation source is also located.

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Longitudinal vortex system was produced by a three-dimensional delta wing. The wing with attack angle of 15 degrees was merged in the uniform flow speed of 150 km/h. CFD clarified the structure of longitudinal vortex and the characteristics of wing surface-pressure fluctuation caused by longitudinal vortex. As a result, it was found that the rotational velocity, the pressure coefficient and the vorticity have their largest values at the tip of the vortex and reduce downstream along the vertical axis. The pressure coefficient and vorticity distributions presented the possibility that the longitudinal vortex consists of some vortices. Moreover, CFD revealed that dipole source associated with surface-pressure fluctuation time-derivative has maximum value at the tip of the wing.

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In this paper, static pressure fluctuation and velocity fluctuation around NACA0012 airfoil are measured by using the pressure probe and the hotwire anemometer in order to clarify flow structures and unsteady behavior of airfoil tip flows. The Reynolds number based on the chord length of the airfoil and uniform flow velocity is 8×10^4 and the airfoil is under the high lift condition. In the test section, the airfoil is vertically installed and the pressure probe is installed in the flow from downstream of the airfoil. Static pressure distributions and velocity distributions indicate the fluctuation regions caused by the primary vortex and the secondary vortex are outer of tip vortex center.

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The present paper focuses on the effect of air jets on acoustic absorption coefficient of a perforated thin plate with cavity. We discussed the influences of plate thickness, opening ratio of small holes, hole diameter, shape of cross-section of hole, and number of holes on acoustic absorption characteristics experimentally. The normal incidence absorption coefficient was calculated from the measured transfer function by using transfer function methods. The air flow rate is controlled from 0 to 100 l/min. As a result, the frequency characteristics of the acoustic absorption coefficient showed a maximum value at the local frequency. As the opening rate of small holes increased, the peak level of acoustic absorption coefficient increased at the flow rate of 100 l/min. As the hole diameter decreased with same opening ratio, the acoustic absorption coefficient increased at the higher frequency range.

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Wind tunnel experiment is carried out to investigate the noise suppression effect of a small bump on the cavity bottom floor. The bump is placed 60% of the cavity length away from the upstream edge of the cavity. The results show that the noise suppression effect is large when the geometry of the obstacle is closer to a least-complicated two-dimensional rectangular cylinder.

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The rupture of cerebral aneurysm causes subarachnoid hemorrhage which can result in serious permanent neurological deficit or death. Recently, as one of endovascular neurosurgeries, flow diversion is increasingly being performed. In this approach, one or a few stents called "flow diverter (FD)" are deployed into the parent artery holding an aneurysm. However, some complications such as rupture after the treatment have been reported. The typical hypothesis is that such complications are influenced by hemodynamics change after the treatment. Therefore, the investigation about the relation between the specification of FD and the hemodynamics change is needed. In the present study, flow suppression effect of various stents is evaluated. The result shows that by changing the combination of porosity and pore density, stents having different specifications but the same efficacy can be designed. It means the possibility of presence of a better choice considered both hemodynamic effects and mechanical property.

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To treat cerebral aneurysms, coil embolization has been widely used as a minimal invasive surgical procedure. However, aneurysm recanalization after coil embolization remains as a major problem in this method and risk assessment protocol for such phenomenon has not been established yet. To reveal the occurrence mechanism of recanalization, 23 aneurysms, including 10 recanalized cases and 13 stable cases, are identified with three-dimensional digital subtraction angiography and generated to three-dimensional models. Computational fluid dynamics (CFD) is used to characterize hemodynamics of aneurysms with coil. The original parameter called FpV has significant difference between recanalized cases and stable cases as a result of statistical test to the numerical results. ROC analysis shows that the cut off value of the FpV is 0.014 (AUC=0.82). The aneurysm recanalization may be able to be prevented more effectively by establishing packing density from the cut off value.

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